Shield



E. RIETSCH May 3, 1938.

SHIELD Filed Aug. 5, 1935 Ir'wx/er'wtor` Eberhard PietSCh.

bg W His ttorrweg.

A" 'Patented May 3,' 1938 berhard Rietsch, Hennigsdorf,-A Germany,asslgnor to General Electric Company, a corporation of New YorkApplication August 5, 1935, Serial No. 34,849 In Germanv August 13, 1934e t z claims. (c1. en -41s) -In the observation of processes which takeplace withthe spreading or spraying of liquid or solid particles, as forexample in weldingor casting, it

is usual to protect the observer from. the action of these particles'bysuitable shields. As a rule, such protecting devices are provided, asfar as vision is concerned, with coloied glass plates or the like. Suchshields are unsatisfactory because in use they not only lose theirtransparency and 'l l0' lthus render v'observation dimcult, but also,due to the fact that theglass plates frequently crack or burst whilebeing used, the operator making the observation with such a shield isendangered.

It is an-object of my invention to provide a l5 shield for use inobserving operations which take place with the spreading or spraying ofliquid or solid particles whose instantaneous velocities for the mostpart vary widely within a short space of travel. With such a shield theeye directly follows the process on the object without being subject toinjury from flying particles and the ob server is assured'the 'maximumsafety.

A A .further object of my invention 'is to 'provide such a' device inwhich a plurality of spaced stro- 5 boscopic discs havingregisteringopenings therein are rotated between the observer and the objectobserved, the spacing between said discs and their speed of movementbeing so related to the size of the openings in said discs that thepassage of 3o ilying particles-through said shield is prohibited.Further objects of my invention will become discs are so supported thattheir opetings areA movable between observation openingsl and lillocated in opposite walls of the chamber -within which thediscs areenclosed. These observation openings may be as illustrated of greaterWidth than the slots thereby increasing the field of vision. The spacingbetween the discs, the size of the openings inthe disc, and the speed atwhich the discs are rotated are all so correlated that the passage offlying particles from the object I I through the shield is prohibited.In other words, the spacing between the discs is such that flyingparticles which pass through a slot of the first disc nearest to theobject and which have velocities having such a relation to thevelocities of the discs and the openings therein that they' apparentfrom aconsideration of the following description of'the embodimentsillustrated in the accompanying drawing.

In the drawing, Figs. 1 and 2 are front and side sectional views of oneembodiment of my inven- .tion and Fig. 3 is a front view illustrating amodication of the embodiment illustrated in Figs'. 1 and 2.

The embodiment illustrated in Figs. .1 and 2 is a particularlyadvantageous arrangement, the

utility of which has been proved by tests. In Fig.

, 2, the broken lines I 0 indicate the lines of ight of solid or liquidparticles Ifrom the object II s which is being viewed by an observer whotakes his position onl the. other side of the shield I2.

This shield comprises five stroboscopic discs I3- mounted one behind theother on a spindle I4 which is rotated bya'motor I5 connected theretothrough a gear drive IB. The discs I3 and driving mechanism thereforare, in the arrangement illustrated, enclosed within chambers forming4vpart of the shield. The discs I3 are provided with radially Idisposedslots Il of like. configuration a which are in register with oneanother. These changed by the unequal spacing of the discs.

y through a slot of the second or even of the third disc, eventuallymeet with a solid surface on the fourth or fth disc. With five discs ithas been shown by experience that there is practically no possibility ofying particles-passing through all the discs to the observer located onthe other side of the shield of which these discs form a part.

' It is to be understood, however, that the invention is notlimited tothe u'se of five discs since a smaller or greater number of discs maybeemployed with safety, depending uponcircumstances.' /It is vapparentthat the discs may be equally `or unequally spaced from one anotherwithout departing from my invention. Anunequal spacing of the discs isadvantageous in stopping particles whose velocities `are such as topermit their passage through non-registering openings in adjacent discs..If the velocity of a particle is such as to permit its passage throughtwo non-registering openings in two adjacent discs, the unequal spacingof a third disc will prohibit further passage of the particle becausethe particles time of travel from disc to disc has been It is alsoapparent .that the parts need not be enclosed, 'as illustrated in Figs.1 and 2, but it is desirable to do this to protect the apparatus fromflyingparticles. t I

It is' also apparent that the efficacy of the shield in part\resu1tsfrom the relative movement of two members having openingsr which areperiodically moved across one another. for example, a disc and astationary member such as a side 50 wall of the chamber enclosing thedisc, provided the spacing of these members and their speed of movementare properly related to the sizel of the .openings therein;

The size and shape of the slots in the discs may is do not extend alonga radius.

For use vin welding operations, the parts of vthe shield areadvantageously made of some opaque material in order to protect the eyesof the operator from the glare of the arc and the intense lightresulting from the Welding operation. It is of course apparent that for-many applications the choice of material has no signicance with respectto the utility of the shield.

The observation opening I8 may be closed by glass or vsimilartransparent material. vWhen such a construction is used, it is apparentthat the rotating discs will prevent particles impinging thereon andthus destroying their transparency. It is also apparent that the closingglass or similar transparent material will be so protected that therewill be no possibility of its vcracking or bursting by reason of theimpinging of particles thereon. When such a construction is used forobserving welding operations, the glass, or other transparent material,may be colored in order to decrease the intensity of the lighttransmitted therethrough, but generally this will not be necessarybecause the rotating discs adequatelydecrease the intensity of thetransmited light.

`oi.' the use to which the shield is placed.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. A shield for use ln`observing operations which take place with thespreading or spraying of liquid or solid particles which comprises aspindle, more than two unequally spaced parallel discs havingregistering openings therein supv ported on said spindle with saidopenings in register with one another, and means for rotating saidspindle.

2. A shield for use in observing operations which take place with thespreading or spraying of liquid or solid particles which comprises aspindle, more than two parallel discs having registering slots thereinsupported on said spindle with said slots in register with one another,and a stationary member supported between said discs and the source ofsaid liquid or solidparticles with the registering slots of said discsmovable across an observation opening in said member, said observationopening being of greater width than said slots. Y

EBERHARD RIETSCH.

